To best understand this invention, it is helpful to know that the pneumatic motor of this invention is intended to replace three existing pneumatic surgical motors being manufactured and sold by the assignee and are well known in the medical industry as Black Max, Micro Max and Micro Max Plus and all of which are incorporated herein by reference. These prior art motors have been specifically developed for the medical industry and each in their own right have their own uniqueness. For example, the Black Max is a heavy duty motor that is more powerful and larger than the other two motors, but is heavier, hotter, noisier and vibrates more than these other motors. The Micro Max, supra, was developed to reduce the size, noise, vibration and heat and essentially be more gentle for use by the surgeon and likewise, has developed a niche in the industry. Obviously, the power is reduced. However, this motor for some medical procedures does not meet the needs of the surgeons because it lacked the necessary power which gave rise to the Micro Max Plus motor, which, again, has more power than the Micro Max but, yet, less power than the Black Max. The Micro Max Plus falls in the category of being more gentle for use by the surgeon but again, because of the increased power, heat, vibrations and weight of the Micro Max Plus (higher than the Micro Max but still lower than the Black Max) it, likewise, has gained a niche in the industry. A more technical way of looking at each of these motors is that the length of the cylinder supporting the vanes of the each of the motors are increased as a function of the power generated, namely, the lengths of the cylinders of the Black Max=1.0 inch (″), the Micro Max=¾″ and the Micro Max Plus=½″.
As one skilled in this technology will appreciate, the outside diameter of all of the well known commercially available pneumatic surgical motors including the ones noted in the above paragraphs are substantially equal and include a rotor that is driven by pressurized air for rotating a spindle that is rotatably supported by bearings in an outer housing that serves as the handle of the motor. All of these motors also include in some form or another the necessary seals, anti-rotational device, inlet and outlet for the pressurized air and means for lubricating the bearings and their support structures or internal housings.
We have found that we can provide an improved pneumatic surgical motor that satisfies the requirements of all the functions of the three motors that are discussed in the above paragraphs, but is an improvement there over while providing higher power with a smaller cylinder than the one in the Black Max, is lighter than the smallest of these motors, is cooler, exhibits less vibrations, is quieter and is as gentle to handle as is the smallest of these three motors. To differentiate the motor of the present invention from the pneumatic motors mentioned in the above paragraphs and the heretofore known motors it will be hereinafter referred to as the Xmax motor.
The following features of this invention discussed immediately below which are not to be construed as limitations thereto, contribute to the overall improvements to the inventive motor.                1. Smaller motor spherical ball bearing located at the fore end of the power cylinder provides a cavity within the housing to re-circulate the power cylinder's working compressed air which contributes to lowering the temperature of the bearing and affording improvements to the vibrations and heat characteristics.        2. Face seal disposed adjacent the inner race of the smaller bearing is deformed and cured in situ and enhances sealing of the air/lubricant mist in the motor housing, reduces heat generation and provides a sling action to the oil.        3. The vane on the spindle is designed to have increased vane working surface for augmenting the power of the motor.        4. Angled slots formed on the spindle to enhance the vanes ability to retract into the slot in opposition of centrifugal force so as to reduce friction and increase the life of the motor..        5. Exhaust holes formed in the cylinder discharging compressed air are judiciously located in columns to reduce wear and noise of the motor.        6. Cylinder input holes are oriented relative to the spindle vanes so as to increase input airflow acting on the vane's working surface.        7. The cylinder's inner surface adjacent to the outer surface of the spindle is off-set from round to define a crescent seal so as to increase the effectiveness of the spindle to cylinder gap seal and minimize lubrication requirements.        8. Slots in the cylinder formed adjacent to the inlet holes cool the cylinder before entering the vane motor.        9. A portion of the inlet air to the motor is diverted to flow to the front bearing and toward the aft end so as to air cool the front bearing housing and air cool the cylinder.        10. Provide cross over discharge holes to reduce noise by acoustical cancellation.        11. The motor housing is made from metallic material and may include an insert portion adjacent to where the surgeon will hold the motor an insert made from a heat resistant light weighted material so as to minimize the weight of the motor and afford comfort.        12. The modular construction of the motor includes an air gap between the outer surface of the motor housing and the insert motor housing which serves to provide cooling of the outer housing and isolates vibrations.        13. Modular construction where the insert motor housing is mounted on elastomeric mounts and utilizing the O-seal supporting the air inlet hose so as to reduce noise, temperature, vibration and facilitate assembly.        14. Coupling the motor to the output shaft with a resilient coupling to reduce vibration, noise, temperature and facilitate assembly.        15. Additional increased power is obtained by the orientation of the exhaust holes in the vane motor relative to the vane.        16. Isolation between motor and the lock shaft serves to assure that the axial loads generated by the cutter is isolated from the motor.        